This invention relates to devices for delivering a liquid product. The invention has particular application in areas where long term and controlled release of a liquid product is required, the product being dispensed or dispersed by evaporation, such as in an air freshener or insecticide, or into a flow of other dispersing liquid such as in toilet systems, particularly systems which have an intermittent flow of the dispersing liquid. The invention is particularly concerned with delivering a liquid product such as a perfume, surfactant, bleach or disinfectant, particularly in the form of a solution, dispersion or suspension, and for delivering it to a toilet bowl under the action of water used to flush the toilet bowl.
It has been known for a long time to provide so-called toilet automatics in the form of a solid or semi-solid product, a xe2x80x98rim blockxe2x80x99, to be mounted within the inner rim of a water closet bowl where the flushing water will wash over the product and so dissolve or erode it to release active constituents into the water flow. Blocks may also be placed on top of the cistern, in Japanese style systems where water from a tap flows over the block and then into the cistern, and also may be placed within the cistern below the water level, where they slowly release constituents into the water.
More recently, it has been proposed to use a liquid toilet freshening product in a similar manner, a so-called liquid rim product. For example, EP-A-0538957 describes a device that can be mounted on the inner rim of a water closet bowl to dose a liquid freshening product into the flushing water. In this device, the liquid product is dosed into the water flow from a porous substrate, a delivery plate, which is disposed in the path of the flushing water. The porous substrate is supplied with the liquid product from a container disposed above the substrate, a mouth at the bottom of the reservoir opening onto the upper surface of the substrate. Although this arrangement is simple in construction, it suffers from the drawback that the volume of liquid product that flows to the substrate between flushes is not consistent over the life time of the product, which is typically intended to be 3 to 4 weeks. Dosing seems to depend at least in part, on the head of liquid in the container, since this directly influences the rate of flow from the container onto the surface of the substrate. The container is sealed above the opening, and so a reduced pressure is created above the liquid as it flows onto the substrate. The result is an inconsistency in the dose of liquid product into the toilet bowl over time.
EP-A-0785315 describes a development of the device discussed above. The same basic principle of delivering a liquid product into a flow of water from a porous substrate is employed. However, liquid product from a container is deposited onto the upper surface of the substrate via a regulating channel. The liquid is metered into the channel through an orifice and a separate air opening to the interior of the container is provided. The sizes of the metering orifice and the air opening are strictly regulated to the viscosity of the liquid being dosed. This is described as having the effect of providing a substantially constant xe2x80x98headxe2x80x99 of the liquid above the substrate, independent of the level in the container, although the height of liquid in the container necessarily reduces over time. Although this arrangement provides a more consistent flow rate of liquid product to the absorbent substrate, inconsistent delivery to the flushing water can still result, dependent at least in part on the duration of the periods between flushes. This is thought to be due to the reliance of this device on coagulation of the liquid product to stem its flow onto the substrate, a mechanism which is very dependent on the environment in which the device is operated. It is also thought that the head of liquid bearing down on the substrate can lead to xe2x80x98supersaturationxe2x80x99 of the substrate, so it becomes over loaded with product.
WO 99/66139 and WO 99/66140 describe numerous variations of the liquid rim product, including different styles of delivery plate in place of the porous plate of EP-A-0 538 957, while WO 00/42261 describes yet another product using a grooved plate.
All of the systems still use the same basic idea of delivering liquid directly from the container""s mouth onto the delivery plate.
We have noted that the porous plate systems, in particular, function even less effectively with higher viscosity liquids. It can be appreciated that the flow rate of a liquid tends to fall with increased viscosity. Thus it seems that the viscous liquid is slow to fill the voids of the porous plate in between toilet flushes and then is difficult to rinse out of the plate during the flushing action. A grooved plate has the benefit that the liquid on the plate is more exposed, but the grooves must be relatively deep to contain sufficient liquid for a dosing action, risking the retention of liquid in the grooves. Also, the number of grooves near the container mouth is necessarily limited, and so the rate of flow into the grooves is restricted.
It is one object of the present invention to provide an improved system for dosing a liquid product, particularly a viscous product.
One aspect of the present invention provides a liquid delivery device comprising a container for the liquid, a delivery surface, and means for releasing the liquid onto the delivery surface, wherein the delivery surface comprises a layer of textile material.
It has been found that a textile surface can provide for a faster and better spread of a viscous liquid over a dosing area, as compared to a porous substrate or grooved plate of the prior art. Without wishing to be bound by theory, it is believed that the relatively fine surface structure of the textile surface may contribute.
The better spread of the viscous liquid counters its greater resistance to dissolution and dispersal in flushing water, as compared to the more easily dispersed low viscosity liquids.
Very preferably the viscous liquid is not absorbed, or not absorbed substantially into the fabric and so it is washed off more readily by flushing water in a toilet bowl, or evaporates more readily to atmosphere to provide improved fragrance.
Textile material is a material or fabric made from fibres, yams or filaments (herein referred to generally as fibres). The material may be non-woven, in which fibres are bonded, fused or interlocked, but a material made by interweaving, intertwining or interlooping (referred to generally herein as weaving or knitting) is preferred.
The material is preferably of quite dense structure when seen in plan, so as to present a substantially continuous surface, with few if any voids between adjacent fibres. By virtue of the weaving or knitting process, the fabric will have a textured or three dimensional surface.
Preferably the surface is compacted, that is with few fibres or fibrous elements projecting from the surface, and the surface texture having a low profile or height.
A particularly preferred textile material is a polyester knitted fabric such as used for a closely knit pattern in net curtain material. A particular example is a knitted polyester fibre.
The liquid from the container can be delivered directly onto the upper surface of the fabric from above, for example using devices of the type seen in EP-A-538 957, WO 99/66139 and WO 00/42261. However it is particularly preferred to deliver the liquid from a cup located below the fabric. A capillary system delivers the liquid on to the fabric surface. The capillary may be a series of grooves or channels, a porous member, or a wick of cellulose, polyester or the like as used in air fresheners, for example. A system for delivering liquid onto the upper surface of a delivery plate is described in my International Patent Application filed concurrently herewith the contents of which are incorporated herein by reference. Such a system is suitable for use with the textile surface of the present invention.